By DAVID BARBOZA
Published: April 24, 2007
BEIJING, April 23 â€” China on Monday has given American regulators permission to enter the country to investigate whether Chinese suppliers exported contaminated pet food ingredients to the United States earlier this year, leading to one of the largest pet food recalls in American history.

Representatives of the United States Food and Drug Administration had been blocked from entering China, despite growing evidence that the tainted pet food that killed at least 16 cats and dogs and sickened thousands of other animals in the United States originated with Chinese exporters of wheat gluten and other animal feed ingredients.

The F.D.A. confirmed Monday that it has now opened a criminal investigation into the pet food scandal, but the agency did not name the target or say whether any American companies may have intentionally laced animal feed with banned ingredients. On Tuesday, the House Committee on Energy and Commerce is scheduled to hold hearings on how to secure the safety of the countryâ€™s food supply.

Last Thursday, the F.D.A. expanded its already large pet food recall after it found more evidence that an industrial chemical called melamine had contaminated the supplies of additional pet food makers, including Royal Canin US and C. J. Foods.

The agency, which has already recalled more than 60 million packages of pet food, is also investigating imports of rice protein from China.

Regulators in California said this week that they had found melamine in rice protein animal feed that was fed to livestock, and the fear is that the chemical could have entered the human food supply chain through hogs.

Laboratory testing in California had detected melamine in urine from hogs at the American Hog Farm in Ceres, Calif. California regulators have alerted anyone who purchased pork from American Hog Farm from April 3 to April 18 to be cautious.

In its news release over the weekend, the F.D.A. also identified a second Chinese company that had exported animal feed tainted with melamine to American pet food and animal feed suppliers.

Reached by telephone Monday in China, the company, Binzhou Futian Biological Technology, declined to comment. Earlier this month, regulators said another Chinese company, the Anying Biological Technology Development Company in Xuzhou, had sold wheat gluten contaminated with melamine to suppliers of American pet food.

Chinaâ€™s State Administration of Quality Supervision, Inspection and Quarantine, which is responsible for overall food safety issues here, declined to respond to questions sent to the agency Monday.

American regulators now believe the Chinese companies may have intentionally added melamine to their feed ingredients to artificially bolster the protein count in those supplies in order to meet requirements.

A Chinese expert here said Monday that it was possible melamine could have been used to bolster protein counts.

â€œIf the melamine level is high, it must have been added intentionally.â€

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